Combine butter and sugar in your mixer's bowl.
With the paddle attachment on, beat the mixture until creamy; about 10 to 15 seconds.
Gradually add the flour and mix until well combined.
Wrap dough in plastic wrap or place it in a ziploc bag and refrigerate until firm. You can also put it in the freezer for 20 minutes.
Preheat oven to 275.
Remove dough from fridge.
Pinch off dough and roll into 1-inch balls. I use a kitchen scale and pinch off 1/2-ounce for each cookie.
Roll each ball in raw sugar.
Place cookies on an ungreased baking sheet, 2-inches apart.
Using a drinking glass, slightly flatten each cookie-ball.
With your thumb, make an indentation in the center of the cookies.
Bake for 42 to 45 minutes, or until golden in color.
Remove from oven and let stand 1 minute.
Transfer to cooling racks; let cool.
Drop 1/4 teaspoon of jam into each indentation.